from __future__ import annotations

from src.domain import LANGUAGE, MAX_BYTES, MAX_CHANGED_LINES, MAX_FILES, MAX_RELATED_FILES
from src.schemas import ChangeSet, ValidationReport


def empty_report() -> ValidationReport:
    return ValidationReport(ok=True)


def validate_size(text: str, label: str) -> ValidationReport:
    report = empty_report()
    if text is None:
        report.add("empty", f"{label} is missing.", label)
        return report
    raw = text.encode("utf-8")
    if len(raw) == 0 or not str(text).strip():
        report.add("empty", f"{label} is empty.", label)
    if len(raw) > MAX_BYTES:
        report.add("too_large", f"{label} exceeds {MAX_BYTES} bytes.", label)
    return report


def validate_changeset(change: ChangeSet | None, required: bool = True) -> ValidationReport:
    report = empty_report()
    if change is None:
        if required:
            report.add("missing_diff", "The change could not be parsed.", "diff")
        return report
    if not change.files:
        report.add("no_files", "The diff contains no Python files.", "diff")
    if len(change.files) > MAX_FILES:
        report.add("too_many_files", f"More than {MAX_FILES} files were changed.", "diff")
    if change.changed_line_count > MAX_CHANGED_LINES:
        report.add(
            "too_many_lines",
            f"The change has {change.changed_line_count} lines; the cap is {MAX_CHANGED_LINES}.",
            "diff",
        )
    if len(change.related) > MAX_RELATED_FILES:
        report.add("too_many_related", f"More than {MAX_RELATED_FILES} related files were provided.", "related")
    for item in change.files:
        if not item.path.endswith(".py"):
            report.add("unsupported_language", f"{item.path} is not Python. MVP language is {LANGUAGE}.", item.path)
        if item.after and len(item.after.encode("utf-8")) > MAX_BYTES:
            report.add("too_large", f"{item.path} exceeds {MAX_BYTES} bytes.", item.path)
    return report


def merge_reports(*reports: ValidationReport) -> ValidationReport:
    out = empty_report()
    for report in reports:
        if report is None:
            continue
        out.issues.extend(report.issues)
        if not report.ok:
            out.ok = False
    return out